Material Damping Ratio

- March 7, 2020 at 12:58 pm
  
  Autonewbie
  Subscriber
  
  Hi,
  
  I am running a random vibration using global damping ratio. However, I want to know how if adding certain material like rubber will increase damping effects. Is it I have to use material damping coefficient for all the materials used in the assembly product?
  
  Thanks!!
- March 7, 2020 at 5:38 pm
  
  peteroznewman
  Subscriber
  
  Yes, use Material Damping when you have multiple types of material in an assembly.
- March 8, 2020 at 4:35 am
  
  Autonewbie
  Subscriber
  
  Is it using 'Material Dependent Damping' instead of 'Damping Factor Alpha' or 'Damping Factor Beta'?
  
  If using material damping, should I leave the Damping Controls Setting (damping ratio/ coefficient) to be blank under Mechanical?
  
  I am currently assuming 3% for the assembly model under random vibration. I want to see the damping effect if I add some rubber for damping purpose. So, I wonder if I can remove damping ratio of 0.03 from damping controls under analysis setting and just use 0.03 for each material used in the assembly under engineering data?
  
  Thanks!
- March 9, 2020 at 1:03 am
  
  peteroznewman
  Subscriber
  
  You can define Damping Ratio or Damping Factor Alpha and Beta.
  
  You can use those in Engineering Data or under Damping Controls under Analysis Settings in Mechanical.
  
  The model will add damping from any of those four places.
  
  If you put the same damping in Engineering Data and under Damping Controls, then you get double the damping.
  
  If you use both Damping Ratio and Damping Factor Alpha and Beta, then you get both types of damping.
  
  If you apply damping using Damping Controls under the Analysis Settings in Mechanical, it applies the same values to all bodies in the model.
  
  If you use different values for different materials in Engineering Data, then each material will get the correct damping from Engineering Data.